• Title/Summary/Keyword: commercial concrete

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Computationally efficient 3D finite element modeling of RC structures

  • Markou, George;Papadrakakis, Manolis
    • Computers and Concrete
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    • v.12 no.4
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    • pp.443-498
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    • 2013
  • A detailed finite element modeling is presented for the simulation of the nonlinear behavior of reinforced concrete structures which manages to predict the nonlinear behavior of four different experimental setups with computational efficiency, robustness and accuracy. The proposed modeling method uses 8-node hexahedral isoparametric elements for the discretization of concrete. Steel rebars may have any orientation inside the solid concrete elements allowing the simulation of longitudinal as well as transverse reinforcement. Concrete cracking is treated with the smeared crack approach, while steel reinforcement is modeled with the natural beam-column flexibility-based element that takes into consideration shear and bending stiffness. The performance of the proposed modeling is demonstrated by comparing the numerical predictions with existing experimental and numerical results in the literature as well as with those of a commercial code. The results show that the proposed refined simulation predicts accurately the nonlinear inelastic behavior of reinforced concrete structures achieving numerical robustness and computational efficiency.

Study on the Exposed Concrete Construction Formwork According to Attachment Materials (거푸집 붙임재료에 따른 노출콘크리트 시공에 관한 연구)

  • Park, Se-Jun;Lee, Yun-Suk;Lee, Young-Do
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2016.05a
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    • pp.223-224
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    • 2016
  • Recent local advantages to improve the aesthetics of building materials connected with one of the trend of Exposed Concrete and Construction Method in various facilities and to diversify Showing a tendency to both application and development. This exposed concrete form of the features and materials is, the impact of large commercial viability and can consider I can apply to the surface of construction on a surface The diversification of the material was soon exposed directly linked to the varying aesthetics of concrete, and currently take advantage of the form of material is based on such important factor in our country Based on the concept of Exposed Concrete utilized by some construction site, design and be considered is very important elements of the put to practical use.

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Quality assessment of high performance concrete using digitized image elements

  • Peng, Sheng-Szu;Wang, Edward H.;Wang, Her-Yung;Chou, Yu-Te
    • Computers and Concrete
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    • v.10 no.4
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    • pp.409-417
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    • 2012
  • The quality of high performance concrete largely depends on water cement ratio, porosity, material composition and mix methods. The uniformity of color, texture and compressive strengths are quality indicators commonly used to assess the overall characteristics of concrete mixes. The homogeneity and share of coarse aggregates play a key role in concrete quality and must be analyzed in a microscopic point of view. This research studies the quality of high performance concrete by taking drilled cores in both horizontal and vertical directions from a 1.0 $m^3$ specimen. The coarse aggregate, expressed in digitized $100{\times}116$ dpi resolution images are processed based on brightness in colors through commercial software converted into text files. With the image converting to text format, the share of coarse aggregate is quantified leading to a satisfactory assessment of homogeneity - a quality index of high performance concrete. The compressive strengths of concrete and the shares of coarse aggregate of the samples are also compared in this research study to illustrate its correlation in concrete quality. It is concluded that a higher homogeneity of aggregate exists in the vertical plane than that of the horizontal planes of the high performance concrete. In addition, the concrete specimen showing denser particle packing has relatively higher compressive strengths. The research methodology provides an easy-to-use, direct measurement of high performance concrete when conducting quality assessment in the construction site.

Stability analysis on the concrete slab of the highest concrete-faced rock-fill dam in South Korea

  • Baak, Seung-Hyung;Cho, Gye-Chun;Song, Ki-Il
    • Geomechanics and Engineering
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    • v.13 no.5
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    • pp.881-892
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    • 2017
  • Design and management of concrete slabs in concrete-faced rock-fill dams are crucial issues for stability and overall dam safety since cracks in the concrete face induced by stress, shrinkage, and deterioration can cause severe leakage from the reservoir into the dam. Especially, the increase of dam height to a certain level to enhance the storage capacity and to improve hydraulic stability can lead to undesirable deformation behavior and stress distribution in the existing dam body and in the concrete slabs. In such conditions, simulation of a concrete slab with a numerical method should involve the use of an interface element because the behavior of the concrete slab does not follow the behavior of the dam body when the dam body settles due to the increase of dam height. However, the interfacial properties between the dam body and the concrete slab have yet to be clearly defined. In this study, construction sequence of a 125 m high CFRD in South Korea is simulated with commercial FDM software. The proper interfacial properties of the concrete slab are estimated based on a comparison to monitored vertical displacement history obtained from the concrete slab. Possibility of shear strength failure under the critical condition is investigated based on the simplified model. Results present the significance of the interfacial properties of the concrete slab.

Composite Wood-Concrete Structural Floor System with Horizontal Connectors

  • SaRibeiro, Ruy A.;SaRibeiro, Marilene G.
    • International Journal of Concrete Structures and Materials
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    • v.9 no.1
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    • pp.61-67
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    • 2015
  • The concept of horizontal shear connection utilization on wood-concrete beams intends to be an alternative connection detail for composite wood-concrete decks. The volume of sawn-wood is over three times more expensive than concrete, in Brazil. In order to be competitive in the Brazilian market we need a composite deck with the least amount of wood and a simple and inexpensive connection detail. This research project uses medium to high density tropical hardwoods managed from the Brazilian Amazon region and construction steel rods. The beams studied are composed of a bottom layer of staggered wood boards and a top layer of concrete. The wood members are laterally nailed together to form a wide beam, and horizontal rebar connectors are installed before the concrete layer is applied on top. Two sets of wood-concrete layered beams with horizontal rebar connectors (6 and 8) were tested in third-point loading flexural bending. The initial results reveal medium composite efficiency for the beams tested. An improvement on the previously conceived connection detail (set with six connectors) for the composite wood-concrete structural floor system was achieved by the set with eight connectors. The new layout of the horizontal rebar connectors added higher composite efficiency for the beams tested. Further analysis with advanced rigorous numerical Finite Element Modeling is suggested to optimize the connection parameters. Composite wood-concrete decks can attend a large demand for pedestrian bridges, as well as residential and commercial slabs in the Brazilian Amazon.

The Remicon Production of High Strength Concrete for Practical Application (현장 실용화를 위한 고강도콘크리트의 레미콘 제조 및 생산)

  • 윤영수;이승훈;성상래;백승준;신성우;장일영
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.04a
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    • pp.189-194
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    • 1995
  • This paper presents the material properties and production of 500 and 700 kg/$\textrm{cm}^2$ high strength concrete for the practical utilization. A series of Lab. tests were conducted to optimize the material mixture of high strength concrete and then mock-up tests were performed through the Remicon Batch Plant. This paper stresses the material conditions for the final stage of production of 500 and 700 kg/$\textrm{cm}^2$ high strength concrete, just prior to the practical use on 28-story Samsung Shin-Daebang Housing-Commercial Combined Building with 8-story basements.

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Effect of Asphalt Pavement Conditions on Tensile Adhesive Strength of Waterproofing System on Concrete Bridge Deck (아스팔트 포장 조건이 교면방수 시스템의 인장접착강도에 미치는 영향)

  • 이병덕;박성기;김광우;정해문
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.299-304
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    • 2003
  • In this research, eight waterproofing membranes were selected from commercial market and the tensile adhesive characteristics of the waterproofing system (WPS) on concrete bridge deck were investigated in view of various factor in asphalt pavement. Tensile adhesive strength (TAS) test of different asphalt pavement types showed that TAS of WPS under SMA (Stone Mastic Asphalt) pavement was greater than that under dense asphalt pavement. Tensile adhesive strength (TAS) of sheet membranes was improved as the compaction temperature of asphalt concrete increase, but TAS of liquid membranes were not. TAS of sheet membranes after wheel tracking test were in the order of the sites under wheel path (UWP), before wheel tracking (BWT) and nearby wheel path (NWP), Since TAS of the same WPS of UWP was higher than TAS of BWT, wheel loading had function of pressing WPS resulting in higher adhesive strength, But liquid membranes were variable on types, The feature of detached interface after T AS test showed that sheet types were all detached in between deck concrete and WPS, and liquid types were detached in between asphalt pavement and WPS,

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Comparison Analysis on the Structural Stability of Concrete Median Barriers Using Commercial Software (상용 프로그림을 이용한 콘크리트 중앙분리대 방호울타리들의 구조적 안정성에 대한 비교 분석)

  • 주재웅;이성관
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.10a
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    • pp.177-184
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    • 2002
  • The concrete median barriers are the most popular safety appurtenances that can be installed on narrow medians and are effective in keeping uncontrolled vehicles from crossing into opposing lanes of traffic. It is necessary to install and maintain median barriers because it is very difficult to reserve enough room required for medians in KOREA. And concrete median barriers are accepted as the actual alternatives for median barriers, mostly because they require almost no maintenance even after serious collisions. Typical concrete median barriers are 810mm high and have 596mm high glare screens on top of them. But we have experienced a number of “climb” and “roll-over” accidents of heavy vehicles until now, and most of all, there have been some serious accidents caused by the part of broken glare screens. We have performed many computer simulations for the evaluation of the crashworthiness of concrete median barriers, and through the simulations we have tried to find a proper type of concrete median barrier.

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Effects of vibration due to concrete crusher on bond strength of latex-modified concrete (LMC) (파쇄기 진동이 Latex-modified concrete (LMC)의 부착강도에 미치는 영향)

  • Cha, Hun;Kim, Dae-Geon;Choi, Sang-Hwan;Moon, Kyeong-Sik
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2014.11a
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    • pp.9-10
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    • 2014
  • Cracks on the surface of latex-modified concrete using ready mix concrete (R-LMC) are attributable to its sensitivity to air temperature, relative humidity and wind velocity. Insufficient curing under the windy condition causes plastic shrinkage cracks. The cracked areas should be replaced to prevent development of larger cracks. This paper investigated how the vibration resulted from crushing concrete for replacement of the partial cracked area affects bond strength of R-LMC at early age. To analyze bond strength of R-LMC, the commercial Finite Element (FE) program, ABAQUS Standard/Implicit version 6.12 was used, and bond strength was tested by ASTM C1583-04. The real vibration was applied to this FE model using an acceleration measurement equipment.

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Behavior of Concrete/Cold Formed Steel Composite Beams: Experimental Development of a Novel Structural System

  • Wehbe, Nadim;Bahmani, Pouria;Wehbe, Alexander
    • International Journal of Concrete Structures and Materials
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    • v.7 no.1
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    • pp.51-59
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    • 2013
  • The use of light-gauge steel framing in low-rise commercial and industrial building construction has experienced a significant increase in recent years. In such construction, the wall framing is an assembly of cold-formed steel (CFS) studs held between top and bottom CFS tracks. Current construction methods utilize heavy hot-rolled steel sections, such as steel angles or hollow structural section tubes, to transfer the load from the end seats of the floor joist and/or from the load-bearing wall studs of the stories above to the supporting load-bearing wall below. The use of hot rolled steel elements results in significant increase in construction cost and time. Such heavy steel elements would be unnecessary if the concrete slab thickening on top of the CFS wall can be made to act compositely with the CFS track. Composite action can be achieved by attaching stand-off screws to the track and encapsulating the screw shank in the deck concrete. A series of experimental studies were performed on full-scale test specimens representing concrete/CFS flexural elements under gravity loads. The studies were designed to investigate the structural performance of concrete/CFS simple beams and concrete/CFS continuous headers. The results indicate that concrete/CFS composite flexural elements are feasible and their structural behavior can be modeled with reasonable accuracy.